If it's the same as the Leon, you need to be careful when you rest your right hand on the centre spoke of the wheel as it may touch the rocker switch that changes what group of info is on the display. Sometimes my speed disappears and it tells me what's playing on the music page! Hopefully they may have recessed the control on the Ateca slightly to stop this happening, if not it may explain why you get unplanned changes to the display.
For other people's benefit this is what i have found:
Its the same as the MPG stuff.
Select driving data, Then scroll to the one you want, say Avg. MPG, then press the scrolling wheel, you will cycle through the sub states of those so on AVG. MPG you go between: Long Term, Since Start and Since refuelling, (which i havent figured out if it resets automatically when i have filled it up or because i have reset the trip computer hmmm :?: )
Ps to reset all long term data you need to use your touch screen menus.